


Beneath Me

by Mercy_Run



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Dirty Talk, Displays of power, Drugs, Ecto-Genitalia (Undertale), Fellcest - Freeform, M/M, Possessive Behavior, Praise Kink, Semi-Public Sex
Language: English
Status: Completed
Published: 2017-09-17
Updated: 2017-09-17
Packaged: 2018-12-31 00:35:01
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,386
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12120705
Author URL: https://archiveofourown.org/users/Mercy_Run/pseuds/Mercy_Run
Summary: Papyrus isn't one to share, especially when it's his older brother.  After discovering Sans behaving stupidly in Grillby's, the Royal Guardsman drags him into the alley to remind his sibling who he belongs to.NSFW Blog: mercy-run.tumblr.com





	Beneath Me

**Author's Note:**

  * For [PurrfecktlySinful](https://archiveofourown.org/users/PurrfecktlySinful/gifts).



> For Purr, from back in the Olden Days when only 500 people were following me on Tumblr.

"And just what the fuck were you trying to prove back there, whelp?"

The growled words against his skull had Sans trembling, his back pressed up roughly against brick; the looming form of his brother pinning him to the wall of the alley. His feet were kicking uselessly in the air as Papyrus held him easily aloft.

"b-boss!" He gasped, skull still spinning from the amount of mustard the small skeleton had downed.

Sans couldn't recall what he had done to anger his sibling.

Whatever it was... He hoped it wasn't too bad of a transgression.

The note of confusion and fear caused the taller skeleton to pause to scrutinize the trapped monster. Noting the hazy red eye-lights and heavy smell of mustard, Papyrus leaned in close until their faces were a hair's breadth away.

There was the faintest hint of Grillby's magic under the bitter smell of the condiment.

That fucker-!

His fangs ground together in irritation as he eased slightly on the punishing pressure he had on Sans' arms.

"You're drugged." He growled lowly. Sans' hazy eye-lights dilated in disbelief, redirecting Papyrus' anger completely towards the bartender. How dare the fiery bastard for even planning on laying his filthy hands on his small brother!?

Papyrus kept Sans pinned to the wall with one hand as the other lowered to cup his brother's face.

"your magic is agitated, dear brother. he planned on violating what's mine." He hissed, narrowing his sockets angrily, "you stink of his magic."

Sans trembled, red magic welling up in his sockets.

How had Sans not noticed Grillby slipping something in his drink? He felt ashamed that something might have happened because of his idiocy.

Papyrus noted the despondent expression Sans adopted, his angry expression easing into a teasing leer. Sharp phalanges gently caressed the smaller monster's cheek.

"Let's get his scent off of you, hmmm?" He purred and the trapped monster shivered at the suggestive tone in his sibling's voice. Papyrus nuzzled into Sans' vertebrae and nipped the bone there.

"h-here, boss?" Sans whispered.

"Mm," Papyrus hummed in affirmation, long ruby tongue snaking entirely around Sans' small neck before he trailed up the side of his skull, "of course. Can't have any monster smelling that wretched creature on you. I'm going to let you down now...and I want you to get me worked up enough to fuck you senseless."

Sans was lowered gingerly until he found his footing, hazy eye-lights looking up at his younger brother timidly.

"what if someone hears?" He questioned.

Papyrus' sockets smoldered with red magic as he smirked, "I am sure you can find a way to keep silent."

Sans' sockets widened before lidding slightly, "you got it, boss..."

Papyrus' smirk softened into a satisfied smile as his brother fell to his knees in the snow, small bony hands working the buckle of his belt free. He placed one hand on top of Sans' skull, being careful of the crack there as the sound of his zipper being lowered reached his hearing.

"That's right..." He murmured, burning socket trained on Sans as the other monster's eye-lights darted up to look at him. The smaller skeleton worked his leather pants open, freeing his pulsing ruby cock with a reverent expression.

Sans' eye-lights flickered to red hearts briefly.

So cute...

His cock twitched at the first kitten-like lick over the head of his shaft, a pleased sigh escaping the younger brother. But he wasn't in the mood for gentle. Gentle was for when they were safely behind locked doors.

This was about marking his territory.

"Open wide, brother," Papyrus ordered sternly and Sans paused, his drugged state slow on picking up on the change in mood before his sharp fangs parted as wide as they would go. Papyrus thrust into his older sibling's skull, the smooth slide of ectoplasm against his cock delightful.

Sans flattened his glowing tongue firmly against the underside of the taller skeleton's cock as Papyrus began to find a firm, rough pace.

"mmhg!" Sans whimpered as large hands gripped his skull and Papyrus hilted himself completely, holding steady as deeply as his brother's limitations allowed him.

"Easy, whelp..." He breathed lowly and he paused until Sans' eye-lights met his, signaling his readiness. He drew back and slammed back home, his sibling's muffled cries music. The other's red magic oozed between sharp fangs, dribbling down his chin and slicking his cock enough to make wet slapping noises.

"Do you love getting your skull fucked, brother?" Papyrus growled lowly in his rib cage. His only answer was the repetition of heart shaped pins of light as Sans' whines and moans were muffled around his cock.

Slight movement near Sans' knees caught the taller skeleton's attention and he snarled in warning.

"Don't you fucking dare touch yourself, asshole," he threatened and the submissive expression Sans' shot up at him over his driving cock snapped his resolve. He pulled completely clear of his sweet brother's mouth, a thick string of red magic connecting the tip of his dick with the mess on Sans' face before it broke off.

Sans was panting as he easily lifted him from the ground, roughly ridding the more fragile skeleton of his shoes and shorts, leaving his pelvis bare to the cold.

The oozing ruby pussy looked far too inviting and Papyrus licked one solid line up the slit before lining up his cock before lining them up.

"Keep quiet, Sans. Unless you want the whole underground to hear you being fucked like a whore." He murmured before hilting himself with one violent jerk. Frantic, Sans buried his mouth against Papyrus' red scarf to muffle his cry.

Before he could even recover, Papyrus was rutting into him as if he had been the one drugged, the rough slide of his younger brother's dick against his walls maddening.

"That's it..." Papyrus whispered against the side of Sans' skull, his slight panting being the only thing signaling their activities, "take me all of the way in like a good boy..."

Sans moaned in response, tongue lolling out as he held onto Papyrus for dear life.

"Such a good boy," his younger brother continued, wet magic leaking down the inside of Sans' femurs, "a good boy who wouldn't betray me for that fucking bartender."

His walls fluttered dangerously, Papyrus striking the back of his magic now; pitiful whimpers filling the air between them.

"You love me, don't you; whelp?"

"yes!"

"Shhh..." Papyrus hushed, their bones striking together audibly as he grabbed one of Sans' small legs and held it up for a better angle, driving deeper, "who do you belong to?"

"you!" Sans gasped helplessly, quivering under the onslaught.

He was so, so close-!

"I'll dust that repulsive monster for even thinking of fucking you," Papyrus snarled, articulate and controlled even now, "you feel so damn good, whelp."

Sans' spine arched, pushing him into his younger brother's rib cage; pleas and garbled words falling from his mouth.

"Cum for me, Sans." Papyrus ordered sharply, moving frantically against his smaller sibling; thumb moving to stroke the nub of his brother's formed magic.

"PAPYRUS!"

The small monster jerked and the rough Second in Command didn't even get a chance to reprimand him as Sans' passage squeezed him so harshly that his tight control slipped. Thrusting once more as magic squirted around his cock, Papyrus snarled and grabbed Sans by the collar, yanking his brother up for a kiss as he spilled release inside his sibling.

After a lingering kiss, Papyrus pulled away and smirked at the dazed expression on the smaller skeleton's face, the other's skull flushed red in his post-orgasmic bliss.

"Well... After that, I think the entire Underground knows just who owns you," he purred.

Sans' eye sockets widened in realization, horror flickering across his face.

"i'm s-s-so-"

Papyrus hushed the flustered skeleton with a small kiss on his forward.

"I didn't expect you to keep quiet. You have always been piss-poor at it, hmmm?" He grinned as Sans' flushed deeper. He pulled out of his brother, their combined magic running down quivering bone.

"I'm taking you home, pet." He whispered.

And after that, Papyrus would keep his promise of dusting Grillby. The bartender had long since worn out his usefulness. This transgression would cost the elemental his life.

No one touched Sans but him.


End file.
